Magnetic Perturbation of an Ammonia Maser on the 3, 2 Line

Effects of external magnetic field on the amplitude and frequency of ammonia maser oscillator employing the J =3, K =2 line were measured and compared with theory. The variation of the traveling-wave effect by the external field is calculated and theoretical curves of the frequency shift as a function of the external field are given. Definitions of line center by magnetic perturbation method are discussed. It is concluded that the resettability with an accuracy of a few parts in 10 11 can be obtained, when the variation of maser frequency of about 0.5 cps. caused by a magnetic perturbation of 2 to 3 oersteds can be detected and corrected.